]> pilppa.org Git - linux-2.6-omap-h63xx.git/blob - kernel/exit.c
[PATCH] powerpc: Add/remove/update properties in /proc/device-tree
[linux-2.6-omap-h63xx.git] / kernel / exit.c
1 /*
2  *  linux/kernel/exit.c
3  *
4  *  Copyright (C) 1991, 1992  Linus Torvalds
5  */
6
7 #include <linux/config.h>
8 #include <linux/mm.h>
9 #include <linux/slab.h>
10 #include <linux/interrupt.h>
11 #include <linux/smp_lock.h>
12 #include <linux/module.h>
13 #include <linux/capability.h>
14 #include <linux/completion.h>
15 #include <linux/personality.h>
16 #include <linux/tty.h>
17 #include <linux/namespace.h>
18 #include <linux/key.h>
19 #include <linux/security.h>
20 #include <linux/cpu.h>
21 #include <linux/acct.h>
22 #include <linux/file.h>
23 #include <linux/binfmts.h>
24 #include <linux/ptrace.h>
25 #include <linux/profile.h>
26 #include <linux/mount.h>
27 #include <linux/proc_fs.h>
28 #include <linux/mempolicy.h>
29 #include <linux/cpuset.h>
30 #include <linux/syscalls.h>
31 #include <linux/signal.h>
32 #include <linux/cn_proc.h>
33 #include <linux/mutex.h>
34
35 #include <asm/uaccess.h>
36 #include <asm/unistd.h>
37 #include <asm/pgtable.h>
38 #include <asm/mmu_context.h>
39
40 extern void sem_exit (void);
41 extern struct task_struct *child_reaper;
42
43 int getrusage(struct task_struct *, int, struct rusage __user *);
44
45 static void exit_mm(struct task_struct * tsk);
46
47 static void __unhash_process(struct task_struct *p)
48 {
49         nr_threads--;
50         detach_pid(p, PIDTYPE_PID);
51         detach_pid(p, PIDTYPE_TGID);
52         if (thread_group_leader(p)) {
53                 detach_pid(p, PIDTYPE_PGID);
54                 detach_pid(p, PIDTYPE_SID);
55                 if (p->pid)
56                         __get_cpu_var(process_counts)--;
57         }
58
59         REMOVE_LINKS(p);
60 }
61
62 void release_task(struct task_struct * p)
63 {
64         int zap_leader;
65         task_t *leader;
66         struct dentry *proc_dentry;
67
68 repeat: 
69         atomic_dec(&p->user->processes);
70         spin_lock(&p->proc_lock);
71         proc_dentry = proc_pid_unhash(p);
72         write_lock_irq(&tasklist_lock);
73         if (unlikely(p->ptrace))
74                 __ptrace_unlink(p);
75         BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children));
76         __exit_signal(p);
77         /*
78          * Note that the fastpath in sys_times depends on __exit_signal having
79          * updated the counters before a task is removed from the tasklist of
80          * the process by __unhash_process.
81          */
82         __unhash_process(p);
83
84         /*
85          * If we are the last non-leader member of the thread
86          * group, and the leader is zombie, then notify the
87          * group leader's parent process. (if it wants notification.)
88          */
89         zap_leader = 0;
90         leader = p->group_leader;
91         if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
92                 BUG_ON(leader->exit_signal == -1);
93                 do_notify_parent(leader, leader->exit_signal);
94                 /*
95                  * If we were the last child thread and the leader has
96                  * exited already, and the leader's parent ignores SIGCHLD,
97                  * then we are the one who should release the leader.
98                  *
99                  * do_notify_parent() will have marked it self-reaping in
100                  * that case.
101                  */
102                 zap_leader = (leader->exit_signal == -1);
103         }
104
105         sched_exit(p);
106         write_unlock_irq(&tasklist_lock);
107         spin_unlock(&p->proc_lock);
108         proc_pid_flush(proc_dentry);
109         release_thread(p);
110         put_task_struct(p);
111
112         p = leader;
113         if (unlikely(zap_leader))
114                 goto repeat;
115 }
116
117 /* we are using it only for SMP init */
118
119 void unhash_process(struct task_struct *p)
120 {
121         struct dentry *proc_dentry;
122
123         spin_lock(&p->proc_lock);
124         proc_dentry = proc_pid_unhash(p);
125         write_lock_irq(&tasklist_lock);
126         __unhash_process(p);
127         write_unlock_irq(&tasklist_lock);
128         spin_unlock(&p->proc_lock);
129         proc_pid_flush(proc_dentry);
130 }
131
132 /*
133  * This checks not only the pgrp, but falls back on the pid if no
134  * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
135  * without this...
136  */
137 int session_of_pgrp(int pgrp)
138 {
139         struct task_struct *p;
140         int sid = -1;
141
142         read_lock(&tasklist_lock);
143         do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
144                 if (p->signal->session > 0) {
145                         sid = p->signal->session;
146                         goto out;
147                 }
148         } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
149         p = find_task_by_pid(pgrp);
150         if (p)
151                 sid = p->signal->session;
152 out:
153         read_unlock(&tasklist_lock);
154         
155         return sid;
156 }
157
158 /*
159  * Determine if a process group is "orphaned", according to the POSIX
160  * definition in 2.2.2.52.  Orphaned process groups are not to be affected
161  * by terminal-generated stop signals.  Newly orphaned process groups are
162  * to receive a SIGHUP and a SIGCONT.
163  *
164  * "I ask you, have you ever known what it is to be an orphan?"
165  */
166 static int will_become_orphaned_pgrp(int pgrp, task_t *ignored_task)
167 {
168         struct task_struct *p;
169         int ret = 1;
170
171         do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
172                 if (p == ignored_task
173                                 || p->exit_state
174                                 || p->real_parent->pid == 1)
175                         continue;
176                 if (process_group(p->real_parent) != pgrp
177                             && p->real_parent->signal->session == p->signal->session) {
178                         ret = 0;
179                         break;
180                 }
181         } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
182         return ret;     /* (sighing) "Often!" */
183 }
184
185 int is_orphaned_pgrp(int pgrp)
186 {
187         int retval;
188
189         read_lock(&tasklist_lock);
190         retval = will_become_orphaned_pgrp(pgrp, NULL);
191         read_unlock(&tasklist_lock);
192
193         return retval;
194 }
195
196 static inline int has_stopped_jobs(int pgrp)
197 {
198         int retval = 0;
199         struct task_struct *p;
200
201         do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
202                 if (p->state != TASK_STOPPED)
203                         continue;
204
205                 /* If p is stopped by a debugger on a signal that won't
206                    stop it, then don't count p as stopped.  This isn't
207                    perfect but it's a good approximation.  */
208                 if (unlikely (p->ptrace)
209                     && p->exit_code != SIGSTOP
210                     && p->exit_code != SIGTSTP
211                     && p->exit_code != SIGTTOU
212                     && p->exit_code != SIGTTIN)
213                         continue;
214
215                 retval = 1;
216                 break;
217         } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
218         return retval;
219 }
220
221 /**
222  * reparent_to_init - Reparent the calling kernel thread to the init task.
223  *
224  * If a kernel thread is launched as a result of a system call, or if
225  * it ever exits, it should generally reparent itself to init so that
226  * it is correctly cleaned up on exit.
227  *
228  * The various task state such as scheduling policy and priority may have
229  * been inherited from a user process, so we reset them to sane values here.
230  *
231  * NOTE that reparent_to_init() gives the caller full capabilities.
232  */
233 static inline void reparent_to_init(void)
234 {
235         write_lock_irq(&tasklist_lock);
236
237         ptrace_unlink(current);
238         /* Reparent to init */
239         REMOVE_LINKS(current);
240         current->parent = child_reaper;
241         current->real_parent = child_reaper;
242         SET_LINKS(current);
243
244         /* Set the exit signal to SIGCHLD so we signal init on exit */
245         current->exit_signal = SIGCHLD;
246
247         if ((current->policy == SCHED_NORMAL) && (task_nice(current) < 0))
248                 set_user_nice(current, 0);
249         /* cpus_allowed? */
250         /* rt_priority? */
251         /* signals? */
252         security_task_reparent_to_init(current);
253         memcpy(current->signal->rlim, init_task.signal->rlim,
254                sizeof(current->signal->rlim));
255         atomic_inc(&(INIT_USER->__count));
256         write_unlock_irq(&tasklist_lock);
257         switch_uid(INIT_USER);
258 }
259
260 void __set_special_pids(pid_t session, pid_t pgrp)
261 {
262         struct task_struct *curr = current->group_leader;
263
264         if (curr->signal->session != session) {
265                 detach_pid(curr, PIDTYPE_SID);
266                 curr->signal->session = session;
267                 attach_pid(curr, PIDTYPE_SID, session);
268         }
269         if (process_group(curr) != pgrp) {
270                 detach_pid(curr, PIDTYPE_PGID);
271                 curr->signal->pgrp = pgrp;
272                 attach_pid(curr, PIDTYPE_PGID, pgrp);
273         }
274 }
275
276 void set_special_pids(pid_t session, pid_t pgrp)
277 {
278         write_lock_irq(&tasklist_lock);
279         __set_special_pids(session, pgrp);
280         write_unlock_irq(&tasklist_lock);
281 }
282
283 /*
284  * Let kernel threads use this to say that they
285  * allow a certain signal (since daemonize() will
286  * have disabled all of them by default).
287  */
288 int allow_signal(int sig)
289 {
290         if (!valid_signal(sig) || sig < 1)
291                 return -EINVAL;
292
293         spin_lock_irq(&current->sighand->siglock);
294         sigdelset(&current->blocked, sig);
295         if (!current->mm) {
296                 /* Kernel threads handle their own signals.
297                    Let the signal code know it'll be handled, so
298                    that they don't get converted to SIGKILL or
299                    just silently dropped */
300                 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
301         }
302         recalc_sigpending();
303         spin_unlock_irq(&current->sighand->siglock);
304         return 0;
305 }
306
307 EXPORT_SYMBOL(allow_signal);
308
309 int disallow_signal(int sig)
310 {
311         if (!valid_signal(sig) || sig < 1)
312                 return -EINVAL;
313
314         spin_lock_irq(&current->sighand->siglock);
315         sigaddset(&current->blocked, sig);
316         recalc_sigpending();
317         spin_unlock_irq(&current->sighand->siglock);
318         return 0;
319 }
320
321 EXPORT_SYMBOL(disallow_signal);
322
323 /*
324  *      Put all the gunge required to become a kernel thread without
325  *      attached user resources in one place where it belongs.
326  */
327
328 void daemonize(const char *name, ...)
329 {
330         va_list args;
331         struct fs_struct *fs;
332         sigset_t blocked;
333
334         va_start(args, name);
335         vsnprintf(current->comm, sizeof(current->comm), name, args);
336         va_end(args);
337
338         /*
339          * If we were started as result of loading a module, close all of the
340          * user space pages.  We don't need them, and if we didn't close them
341          * they would be locked into memory.
342          */
343         exit_mm(current);
344
345         set_special_pids(1, 1);
346         down(&tty_sem);
347         current->signal->tty = NULL;
348         up(&tty_sem);
349
350         /* Block and flush all signals */
351         sigfillset(&blocked);
352         sigprocmask(SIG_BLOCK, &blocked, NULL);
353         flush_signals(current);
354
355         /* Become as one with the init task */
356
357         exit_fs(current);       /* current->fs->count--; */
358         fs = init_task.fs;
359         current->fs = fs;
360         atomic_inc(&fs->count);
361         exit_files(current);
362         current->files = init_task.files;
363         atomic_inc(&current->files->count);
364
365         reparent_to_init();
366 }
367
368 EXPORT_SYMBOL(daemonize);
369
370 static inline void close_files(struct files_struct * files)
371 {
372         int i, j;
373         struct fdtable *fdt;
374
375         j = 0;
376
377         /*
378          * It is safe to dereference the fd table without RCU or
379          * ->file_lock because this is the last reference to the
380          * files structure.
381          */
382         fdt = files_fdtable(files);
383         for (;;) {
384                 unsigned long set;
385                 i = j * __NFDBITS;
386                 if (i >= fdt->max_fdset || i >= fdt->max_fds)
387                         break;
388                 set = fdt->open_fds->fds_bits[j++];
389                 while (set) {
390                         if (set & 1) {
391                                 struct file * file = xchg(&fdt->fd[i], NULL);
392                                 if (file)
393                                         filp_close(file, files);
394                         }
395                         i++;
396                         set >>= 1;
397                 }
398         }
399 }
400
401 struct files_struct *get_files_struct(struct task_struct *task)
402 {
403         struct files_struct *files;
404
405         task_lock(task);
406         files = task->files;
407         if (files)
408                 atomic_inc(&files->count);
409         task_unlock(task);
410
411         return files;
412 }
413
414 void fastcall put_files_struct(struct files_struct *files)
415 {
416         struct fdtable *fdt;
417
418         if (atomic_dec_and_test(&files->count)) {
419                 close_files(files);
420                 /*
421                  * Free the fd and fdset arrays if we expanded them.
422                  * If the fdtable was embedded, pass files for freeing
423                  * at the end of the RCU grace period. Otherwise,
424                  * you can free files immediately.
425                  */
426                 fdt = files_fdtable(files);
427                 if (fdt == &files->fdtab)
428                         fdt->free_files = files;
429                 else
430                         kmem_cache_free(files_cachep, files);
431                 free_fdtable(fdt);
432         }
433 }
434
435 EXPORT_SYMBOL(put_files_struct);
436
437 static inline void __exit_files(struct task_struct *tsk)
438 {
439         struct files_struct * files = tsk->files;
440
441         if (files) {
442                 task_lock(tsk);
443                 tsk->files = NULL;
444                 task_unlock(tsk);
445                 put_files_struct(files);
446         }
447 }
448
449 void exit_files(struct task_struct *tsk)
450 {
451         __exit_files(tsk);
452 }
453
454 static inline void __put_fs_struct(struct fs_struct *fs)
455 {
456         /* No need to hold fs->lock if we are killing it */
457         if (atomic_dec_and_test(&fs->count)) {
458                 dput(fs->root);
459                 mntput(fs->rootmnt);
460                 dput(fs->pwd);
461                 mntput(fs->pwdmnt);
462                 if (fs->altroot) {
463                         dput(fs->altroot);
464                         mntput(fs->altrootmnt);
465                 }
466                 kmem_cache_free(fs_cachep, fs);
467         }
468 }
469
470 void put_fs_struct(struct fs_struct *fs)
471 {
472         __put_fs_struct(fs);
473 }
474
475 static inline void __exit_fs(struct task_struct *tsk)
476 {
477         struct fs_struct * fs = tsk->fs;
478
479         if (fs) {
480                 task_lock(tsk);
481                 tsk->fs = NULL;
482                 task_unlock(tsk);
483                 __put_fs_struct(fs);
484         }
485 }
486
487 void exit_fs(struct task_struct *tsk)
488 {
489         __exit_fs(tsk);
490 }
491
492 EXPORT_SYMBOL_GPL(exit_fs);
493
494 /*
495  * Turn us into a lazy TLB process if we
496  * aren't already..
497  */
498 static void exit_mm(struct task_struct * tsk)
499 {
500         struct mm_struct *mm = tsk->mm;
501
502         mm_release(tsk, mm);
503         if (!mm)
504                 return;
505         /*
506          * Serialize with any possible pending coredump.
507          * We must hold mmap_sem around checking core_waiters
508          * and clearing tsk->mm.  The core-inducing thread
509          * will increment core_waiters for each thread in the
510          * group with ->mm != NULL.
511          */
512         down_read(&mm->mmap_sem);
513         if (mm->core_waiters) {
514                 up_read(&mm->mmap_sem);
515                 down_write(&mm->mmap_sem);
516                 if (!--mm->core_waiters)
517                         complete(mm->core_startup_done);
518                 up_write(&mm->mmap_sem);
519
520                 wait_for_completion(&mm->core_done);
521                 down_read(&mm->mmap_sem);
522         }
523         atomic_inc(&mm->mm_count);
524         if (mm != tsk->active_mm) BUG();
525         /* more a memory barrier than a real lock */
526         task_lock(tsk);
527         tsk->mm = NULL;
528         up_read(&mm->mmap_sem);
529         enter_lazy_tlb(mm, current);
530         task_unlock(tsk);
531         mmput(mm);
532 }
533
534 static inline void choose_new_parent(task_t *p, task_t *reaper, task_t *child_reaper)
535 {
536         /*
537          * Make sure we're not reparenting to ourselves and that
538          * the parent is not a zombie.
539          */
540         BUG_ON(p == reaper || reaper->exit_state >= EXIT_ZOMBIE);
541         p->real_parent = reaper;
542 }
543
544 static inline void reparent_thread(task_t *p, task_t *father, int traced)
545 {
546         /* We don't want people slaying init.  */
547         if (p->exit_signal != -1)
548                 p->exit_signal = SIGCHLD;
549
550         if (p->pdeath_signal)
551                 /* We already hold the tasklist_lock here.  */
552                 group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p);
553
554         /* Move the child from its dying parent to the new one.  */
555         if (unlikely(traced)) {
556                 /* Preserve ptrace links if someone else is tracing this child.  */
557                 list_del_init(&p->ptrace_list);
558                 if (p->parent != p->real_parent)
559                         list_add(&p->ptrace_list, &p->real_parent->ptrace_children);
560         } else {
561                 /* If this child is being traced, then we're the one tracing it
562                  * anyway, so let go of it.
563                  */
564                 p->ptrace = 0;
565                 list_del_init(&p->sibling);
566                 p->parent = p->real_parent;
567                 list_add_tail(&p->sibling, &p->parent->children);
568
569                 /* If we'd notified the old parent about this child's death,
570                  * also notify the new parent.
571                  */
572                 if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
573                     thread_group_empty(p))
574                         do_notify_parent(p, p->exit_signal);
575                 else if (p->state == TASK_TRACED) {
576                         /*
577                          * If it was at a trace stop, turn it into
578                          * a normal stop since it's no longer being
579                          * traced.
580                          */
581                         ptrace_untrace(p);
582                 }
583         }
584
585         /*
586          * process group orphan check
587          * Case ii: Our child is in a different pgrp
588          * than we are, and it was the only connection
589          * outside, so the child pgrp is now orphaned.
590          */
591         if ((process_group(p) != process_group(father)) &&
592             (p->signal->session == father->signal->session)) {
593                 int pgrp = process_group(p);
594
595                 if (will_become_orphaned_pgrp(pgrp, NULL) && has_stopped_jobs(pgrp)) {
596                         __kill_pg_info(SIGHUP, SEND_SIG_PRIV, pgrp);
597                         __kill_pg_info(SIGCONT, SEND_SIG_PRIV, pgrp);
598                 }
599         }
600 }
601
602 /*
603  * When we die, we re-parent all our children.
604  * Try to give them to another thread in our thread
605  * group, and if no such member exists, give it to
606  * the global child reaper process (ie "init")
607  */
608 static inline void forget_original_parent(struct task_struct * father,
609                                           struct list_head *to_release)
610 {
611         struct task_struct *p, *reaper = father;
612         struct list_head *_p, *_n;
613
614         do {
615                 reaper = next_thread(reaper);
616                 if (reaper == father) {
617                         reaper = child_reaper;
618                         break;
619                 }
620         } while (reaper->exit_state);
621
622         /*
623          * There are only two places where our children can be:
624          *
625          * - in our child list
626          * - in our ptraced child list
627          *
628          * Search them and reparent children.
629          */
630         list_for_each_safe(_p, _n, &father->children) {
631                 int ptrace;
632                 p = list_entry(_p,struct task_struct,sibling);
633
634                 ptrace = p->ptrace;
635
636                 /* if father isn't the real parent, then ptrace must be enabled */
637                 BUG_ON(father != p->real_parent && !ptrace);
638
639                 if (father == p->real_parent) {
640                         /* reparent with a reaper, real father it's us */
641                         choose_new_parent(p, reaper, child_reaper);
642                         reparent_thread(p, father, 0);
643                 } else {
644                         /* reparent ptraced task to its real parent */
645                         __ptrace_unlink (p);
646                         if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
647                             thread_group_empty(p))
648                                 do_notify_parent(p, p->exit_signal);
649                 }
650
651                 /*
652                  * if the ptraced child is a zombie with exit_signal == -1
653                  * we must collect it before we exit, or it will remain
654                  * zombie forever since we prevented it from self-reap itself
655                  * while it was being traced by us, to be able to see it in wait4.
656                  */
657                 if (unlikely(ptrace && p->exit_state == EXIT_ZOMBIE && p->exit_signal == -1))
658                         list_add(&p->ptrace_list, to_release);
659         }
660         list_for_each_safe(_p, _n, &father->ptrace_children) {
661                 p = list_entry(_p,struct task_struct,ptrace_list);
662                 choose_new_parent(p, reaper, child_reaper);
663                 reparent_thread(p, father, 1);
664         }
665 }
666
667 /*
668  * Send signals to all our closest relatives so that they know
669  * to properly mourn us..
670  */
671 static void exit_notify(struct task_struct *tsk)
672 {
673         int state;
674         struct task_struct *t;
675         struct list_head ptrace_dead, *_p, *_n;
676
677         if (signal_pending(tsk) && !(tsk->signal->flags & SIGNAL_GROUP_EXIT)
678             && !thread_group_empty(tsk)) {
679                 /*
680                  * This occurs when there was a race between our exit
681                  * syscall and a group signal choosing us as the one to
682                  * wake up.  It could be that we are the only thread
683                  * alerted to check for pending signals, but another thread
684                  * should be woken now to take the signal since we will not.
685                  * Now we'll wake all the threads in the group just to make
686                  * sure someone gets all the pending signals.
687                  */
688                 read_lock(&tasklist_lock);
689                 spin_lock_irq(&tsk->sighand->siglock);
690                 for (t = next_thread(tsk); t != tsk; t = next_thread(t))
691                         if (!signal_pending(t) && !(t->flags & PF_EXITING)) {
692                                 recalc_sigpending_tsk(t);
693                                 if (signal_pending(t))
694                                         signal_wake_up(t, 0);
695                         }
696                 spin_unlock_irq(&tsk->sighand->siglock);
697                 read_unlock(&tasklist_lock);
698         }
699
700         write_lock_irq(&tasklist_lock);
701
702         /*
703          * This does two things:
704          *
705          * A.  Make init inherit all the child processes
706          * B.  Check to see if any process groups have become orphaned
707          *      as a result of our exiting, and if they have any stopped
708          *      jobs, send them a SIGHUP and then a SIGCONT.  (POSIX 3.2.2.2)
709          */
710
711         INIT_LIST_HEAD(&ptrace_dead);
712         forget_original_parent(tsk, &ptrace_dead);
713         BUG_ON(!list_empty(&tsk->children));
714         BUG_ON(!list_empty(&tsk->ptrace_children));
715
716         /*
717          * Check to see if any process groups have become orphaned
718          * as a result of our exiting, and if they have any stopped
719          * jobs, send them a SIGHUP and then a SIGCONT.  (POSIX 3.2.2.2)
720          *
721          * Case i: Our father is in a different pgrp than we are
722          * and we were the only connection outside, so our pgrp
723          * is about to become orphaned.
724          */
725          
726         t = tsk->real_parent;
727         
728         if ((process_group(t) != process_group(tsk)) &&
729             (t->signal->session == tsk->signal->session) &&
730             will_become_orphaned_pgrp(process_group(tsk), tsk) &&
731             has_stopped_jobs(process_group(tsk))) {
732                 __kill_pg_info(SIGHUP, SEND_SIG_PRIV, process_group(tsk));
733                 __kill_pg_info(SIGCONT, SEND_SIG_PRIV, process_group(tsk));
734         }
735
736         /* Let father know we died 
737          *
738          * Thread signals are configurable, but you aren't going to use
739          * that to send signals to arbitary processes. 
740          * That stops right now.
741          *
742          * If the parent exec id doesn't match the exec id we saved
743          * when we started then we know the parent has changed security
744          * domain.
745          *
746          * If our self_exec id doesn't match our parent_exec_id then
747          * we have changed execution domain as these two values started
748          * the same after a fork.
749          *      
750          */
751         
752         if (tsk->exit_signal != SIGCHLD && tsk->exit_signal != -1 &&
753             ( tsk->parent_exec_id != t->self_exec_id  ||
754               tsk->self_exec_id != tsk->parent_exec_id)
755             && !capable(CAP_KILL))
756                 tsk->exit_signal = SIGCHLD;
757
758
759         /* If something other than our normal parent is ptracing us, then
760          * send it a SIGCHLD instead of honoring exit_signal.  exit_signal
761          * only has special meaning to our real parent.
762          */
763         if (tsk->exit_signal != -1 && thread_group_empty(tsk)) {
764                 int signal = tsk->parent == tsk->real_parent ? tsk->exit_signal : SIGCHLD;
765                 do_notify_parent(tsk, signal);
766         } else if (tsk->ptrace) {
767                 do_notify_parent(tsk, SIGCHLD);
768         }
769
770         state = EXIT_ZOMBIE;
771         if (tsk->exit_signal == -1 &&
772             (likely(tsk->ptrace == 0) ||
773              unlikely(tsk->parent->signal->flags & SIGNAL_GROUP_EXIT)))
774                 state = EXIT_DEAD;
775         tsk->exit_state = state;
776
777         write_unlock_irq(&tasklist_lock);
778
779         list_for_each_safe(_p, _n, &ptrace_dead) {
780                 list_del_init(_p);
781                 t = list_entry(_p,struct task_struct,ptrace_list);
782                 release_task(t);
783         }
784
785         /* If the process is dead, release it - nobody will wait for it */
786         if (state == EXIT_DEAD)
787                 release_task(tsk);
788 }
789
790 fastcall NORET_TYPE void do_exit(long code)
791 {
792         struct task_struct *tsk = current;
793         int group_dead;
794
795         profile_task_exit(tsk);
796
797         WARN_ON(atomic_read(&tsk->fs_excl));
798
799         if (unlikely(in_interrupt()))
800                 panic("Aiee, killing interrupt handler!");
801         if (unlikely(!tsk->pid))
802                 panic("Attempted to kill the idle task!");
803         if (unlikely(tsk->pid == 1))
804                 panic("Attempted to kill init!");
805         if (tsk->io_context)
806                 exit_io_context();
807
808         if (unlikely(current->ptrace & PT_TRACE_EXIT)) {
809                 current->ptrace_message = code;
810                 ptrace_notify((PTRACE_EVENT_EXIT << 8) | SIGTRAP);
811         }
812
813         /*
814          * We're taking recursive faults here in do_exit. Safest is to just
815          * leave this task alone and wait for reboot.
816          */
817         if (unlikely(tsk->flags & PF_EXITING)) {
818                 printk(KERN_ALERT
819                         "Fixing recursive fault but reboot is needed!\n");
820                 set_current_state(TASK_UNINTERRUPTIBLE);
821                 schedule();
822         }
823
824         tsk->flags |= PF_EXITING;
825
826         /*
827          * Make sure we don't try to process any timer firings
828          * while we are already exiting.
829          */
830         tsk->it_virt_expires = cputime_zero;
831         tsk->it_prof_expires = cputime_zero;
832         tsk->it_sched_expires = 0;
833
834         if (unlikely(in_atomic()))
835                 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
836                                 current->comm, current->pid,
837                                 preempt_count());
838
839         acct_update_integrals(tsk);
840         if (tsk->mm) {
841                 update_hiwater_rss(tsk->mm);
842                 update_hiwater_vm(tsk->mm);
843         }
844         group_dead = atomic_dec_and_test(&tsk->signal->live);
845         if (group_dead) {
846                 hrtimer_cancel(&tsk->signal->real_timer);
847                 exit_itimers(tsk->signal);
848                 acct_process(code);
849         }
850         exit_mm(tsk);
851
852         exit_sem(tsk);
853         __exit_files(tsk);
854         __exit_fs(tsk);
855         exit_namespace(tsk);
856         exit_thread();
857         cpuset_exit(tsk);
858         exit_keys(tsk);
859
860         if (group_dead && tsk->signal->leader)
861                 disassociate_ctty(1);
862
863         module_put(task_thread_info(tsk)->exec_domain->module);
864         if (tsk->binfmt)
865                 module_put(tsk->binfmt->module);
866
867         tsk->exit_code = code;
868         proc_exit_connector(tsk);
869         exit_notify(tsk);
870 #ifdef CONFIG_NUMA
871         mpol_free(tsk->mempolicy);
872         tsk->mempolicy = NULL;
873 #endif
874         /*
875          * If DEBUG_MUTEXES is on, make sure we are holding no locks:
876          */
877         mutex_debug_check_no_locks_held(tsk);
878
879         /* PF_DEAD causes final put_task_struct after we schedule. */
880         preempt_disable();
881         BUG_ON(tsk->flags & PF_DEAD);
882         tsk->flags |= PF_DEAD;
883
884         schedule();
885         BUG();
886         /* Avoid "noreturn function does return".  */
887         for (;;) ;
888 }
889
890 EXPORT_SYMBOL_GPL(do_exit);
891
892 NORET_TYPE void complete_and_exit(struct completion *comp, long code)
893 {
894         if (comp)
895                 complete(comp);
896         
897         do_exit(code);
898 }
899
900 EXPORT_SYMBOL(complete_and_exit);
901
902 asmlinkage long sys_exit(int error_code)
903 {
904         do_exit((error_code&0xff)<<8);
905 }
906
907 task_t fastcall *next_thread(const task_t *p)
908 {
909         return pid_task(p->pids[PIDTYPE_TGID].pid_list.next, PIDTYPE_TGID);
910 }
911
912 EXPORT_SYMBOL(next_thread);
913
914 /*
915  * Take down every thread in the group.  This is called by fatal signals
916  * as well as by sys_exit_group (below).
917  */
918 NORET_TYPE void
919 do_group_exit(int exit_code)
920 {
921         BUG_ON(exit_code & 0x80); /* core dumps don't get here */
922
923         if (current->signal->flags & SIGNAL_GROUP_EXIT)
924                 exit_code = current->signal->group_exit_code;
925         else if (!thread_group_empty(current)) {
926                 struct signal_struct *const sig = current->signal;
927                 struct sighand_struct *const sighand = current->sighand;
928                 read_lock(&tasklist_lock);
929                 spin_lock_irq(&sighand->siglock);
930                 if (sig->flags & SIGNAL_GROUP_EXIT)
931                         /* Another thread got here before we took the lock.  */
932                         exit_code = sig->group_exit_code;
933                 else {
934                         sig->group_exit_code = exit_code;
935                         zap_other_threads(current);
936                 }
937                 spin_unlock_irq(&sighand->siglock);
938                 read_unlock(&tasklist_lock);
939         }
940
941         do_exit(exit_code);
942         /* NOTREACHED */
943 }
944
945 /*
946  * this kills every thread in the thread group. Note that any externally
947  * wait4()-ing process will get the correct exit code - even if this
948  * thread is not the thread group leader.
949  */
950 asmlinkage void sys_exit_group(int error_code)
951 {
952         do_group_exit((error_code & 0xff) << 8);
953 }
954
955 static int eligible_child(pid_t pid, int options, task_t *p)
956 {
957         if (pid > 0) {
958                 if (p->pid != pid)
959                         return 0;
960         } else if (!pid) {
961                 if (process_group(p) != process_group(current))
962                         return 0;
963         } else if (pid != -1) {
964                 if (process_group(p) != -pid)
965                         return 0;
966         }
967
968         /*
969          * Do not consider detached threads that are
970          * not ptraced:
971          */
972         if (p->exit_signal == -1 && !p->ptrace)
973                 return 0;
974
975         /* Wait for all children (clone and not) if __WALL is set;
976          * otherwise, wait for clone children *only* if __WCLONE is
977          * set; otherwise, wait for non-clone children *only*.  (Note:
978          * A "clone" child here is one that reports to its parent
979          * using a signal other than SIGCHLD.) */
980         if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0))
981             && !(options & __WALL))
982                 return 0;
983         /*
984          * Do not consider thread group leaders that are
985          * in a non-empty thread group:
986          */
987         if (current->tgid != p->tgid && delay_group_leader(p))
988                 return 2;
989
990         if (security_task_wait(p))
991                 return 0;
992
993         return 1;
994 }
995
996 static int wait_noreap_copyout(task_t *p, pid_t pid, uid_t uid,
997                                int why, int status,
998                                struct siginfo __user *infop,
999                                struct rusage __user *rusagep)
1000 {
1001         int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0;
1002         put_task_struct(p);
1003         if (!retval)
1004                 retval = put_user(SIGCHLD, &infop->si_signo);
1005         if (!retval)
1006                 retval = put_user(0, &infop->si_errno);
1007         if (!retval)
1008                 retval = put_user((short)why, &infop->si_code);
1009         if (!retval)
1010                 retval = put_user(pid, &infop->si_pid);
1011         if (!retval)
1012                 retval = put_user(uid, &infop->si_uid);
1013         if (!retval)
1014                 retval = put_user(status, &infop->si_status);
1015         if (!retval)
1016                 retval = pid;
1017         return retval;
1018 }
1019
1020 /*
1021  * Handle sys_wait4 work for one task in state EXIT_ZOMBIE.  We hold
1022  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1023  * the lock and this task is uninteresting.  If we return nonzero, we have
1024  * released the lock and the system call should return.
1025  */
1026 static int wait_task_zombie(task_t *p, int noreap,
1027                             struct siginfo __user *infop,
1028                             int __user *stat_addr, struct rusage __user *ru)
1029 {
1030         unsigned long state;
1031         int retval;
1032         int status;
1033
1034         if (unlikely(noreap)) {
1035                 pid_t pid = p->pid;
1036                 uid_t uid = p->uid;
1037                 int exit_code = p->exit_code;
1038                 int why, status;
1039
1040                 if (unlikely(p->exit_state != EXIT_ZOMBIE))
1041                         return 0;
1042                 if (unlikely(p->exit_signal == -1 && p->ptrace == 0))
1043                         return 0;
1044                 get_task_struct(p);
1045                 read_unlock(&tasklist_lock);
1046                 if ((exit_code & 0x7f) == 0) {
1047                         why = CLD_EXITED;
1048                         status = exit_code >> 8;
1049                 } else {
1050                         why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1051                         status = exit_code & 0x7f;
1052                 }
1053                 return wait_noreap_copyout(p, pid, uid, why,
1054                                            status, infop, ru);
1055         }
1056
1057         /*
1058          * Try to move the task's state to DEAD
1059          * only one thread is allowed to do this:
1060          */
1061         state = xchg(&p->exit_state, EXIT_DEAD);
1062         if (state != EXIT_ZOMBIE) {
1063                 BUG_ON(state != EXIT_DEAD);
1064                 return 0;
1065         }
1066         if (unlikely(p->exit_signal == -1 && p->ptrace == 0)) {
1067                 /*
1068                  * This can only happen in a race with a ptraced thread
1069                  * dying on another processor.
1070                  */
1071                 return 0;
1072         }
1073
1074         if (likely(p->real_parent == p->parent) && likely(p->signal)) {
1075                 struct signal_struct *psig;
1076                 struct signal_struct *sig;
1077
1078                 /*
1079                  * The resource counters for the group leader are in its
1080                  * own task_struct.  Those for dead threads in the group
1081                  * are in its signal_struct, as are those for the child
1082                  * processes it has previously reaped.  All these
1083                  * accumulate in the parent's signal_struct c* fields.
1084                  *
1085                  * We don't bother to take a lock here to protect these
1086                  * p->signal fields, because they are only touched by
1087                  * __exit_signal, which runs with tasklist_lock
1088                  * write-locked anyway, and so is excluded here.  We do
1089                  * need to protect the access to p->parent->signal fields,
1090                  * as other threads in the parent group can be right
1091                  * here reaping other children at the same time.
1092                  */
1093                 spin_lock_irq(&p->parent->sighand->siglock);
1094                 psig = p->parent->signal;
1095                 sig = p->signal;
1096                 psig->cutime =
1097                         cputime_add(psig->cutime,
1098                         cputime_add(p->utime,
1099                         cputime_add(sig->utime,
1100                                     sig->cutime)));
1101                 psig->cstime =
1102                         cputime_add(psig->cstime,
1103                         cputime_add(p->stime,
1104                         cputime_add(sig->stime,
1105                                     sig->cstime)));
1106                 psig->cmin_flt +=
1107                         p->min_flt + sig->min_flt + sig->cmin_flt;
1108                 psig->cmaj_flt +=
1109                         p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1110                 psig->cnvcsw +=
1111                         p->nvcsw + sig->nvcsw + sig->cnvcsw;
1112                 psig->cnivcsw +=
1113                         p->nivcsw + sig->nivcsw + sig->cnivcsw;
1114                 spin_unlock_irq(&p->parent->sighand->siglock);
1115         }
1116
1117         /*
1118          * Now we are sure this task is interesting, and no other
1119          * thread can reap it because we set its state to EXIT_DEAD.
1120          */
1121         read_unlock(&tasklist_lock);
1122
1123         retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1124         status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1125                 ? p->signal->group_exit_code : p->exit_code;
1126         if (!retval && stat_addr)
1127                 retval = put_user(status, stat_addr);
1128         if (!retval && infop)
1129                 retval = put_user(SIGCHLD, &infop->si_signo);
1130         if (!retval && infop)
1131                 retval = put_user(0, &infop->si_errno);
1132         if (!retval && infop) {
1133                 int why;
1134
1135                 if ((status & 0x7f) == 0) {
1136                         why = CLD_EXITED;
1137                         status >>= 8;
1138                 } else {
1139                         why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1140                         status &= 0x7f;
1141                 }
1142                 retval = put_user((short)why, &infop->si_code);
1143                 if (!retval)
1144                         retval = put_user(status, &infop->si_status);
1145         }
1146         if (!retval && infop)
1147                 retval = put_user(p->pid, &infop->si_pid);
1148         if (!retval && infop)
1149                 retval = put_user(p->uid, &infop->si_uid);
1150         if (retval) {
1151                 // TODO: is this safe?
1152                 p->exit_state = EXIT_ZOMBIE;
1153                 return retval;
1154         }
1155         retval = p->pid;
1156         if (p->real_parent != p->parent) {
1157                 write_lock_irq(&tasklist_lock);
1158                 /* Double-check with lock held.  */
1159                 if (p->real_parent != p->parent) {
1160                         __ptrace_unlink(p);
1161                         // TODO: is this safe?
1162                         p->exit_state = EXIT_ZOMBIE;
1163                         /*
1164                          * If this is not a detached task, notify the parent.
1165                          * If it's still not detached after that, don't release
1166                          * it now.
1167                          */
1168                         if (p->exit_signal != -1) {
1169                                 do_notify_parent(p, p->exit_signal);
1170                                 if (p->exit_signal != -1)
1171                                         p = NULL;
1172                         }
1173                 }
1174                 write_unlock_irq(&tasklist_lock);
1175         }
1176         if (p != NULL)
1177                 release_task(p);
1178         BUG_ON(!retval);
1179         return retval;
1180 }
1181
1182 /*
1183  * Handle sys_wait4 work for one task in state TASK_STOPPED.  We hold
1184  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1185  * the lock and this task is uninteresting.  If we return nonzero, we have
1186  * released the lock and the system call should return.
1187  */
1188 static int wait_task_stopped(task_t *p, int delayed_group_leader, int noreap,
1189                              struct siginfo __user *infop,
1190                              int __user *stat_addr, struct rusage __user *ru)
1191 {
1192         int retval, exit_code;
1193
1194         if (!p->exit_code)
1195                 return 0;
1196         if (delayed_group_leader && !(p->ptrace & PT_PTRACED) &&
1197             p->signal && p->signal->group_stop_count > 0)
1198                 /*
1199                  * A group stop is in progress and this is the group leader.
1200                  * We won't report until all threads have stopped.
1201                  */
1202                 return 0;
1203
1204         /*
1205          * Now we are pretty sure this task is interesting.
1206          * Make sure it doesn't get reaped out from under us while we
1207          * give up the lock and then examine it below.  We don't want to
1208          * keep holding onto the tasklist_lock while we call getrusage and
1209          * possibly take page faults for user memory.
1210          */
1211         get_task_struct(p);
1212         read_unlock(&tasklist_lock);
1213
1214         if (unlikely(noreap)) {
1215                 pid_t pid = p->pid;
1216                 uid_t uid = p->uid;
1217                 int why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED;
1218
1219                 exit_code = p->exit_code;
1220                 if (unlikely(!exit_code) ||
1221                     unlikely(p->state & TASK_TRACED))
1222                         goto bail_ref;
1223                 return wait_noreap_copyout(p, pid, uid,
1224                                            why, (exit_code << 8) | 0x7f,
1225                                            infop, ru);
1226         }
1227
1228         write_lock_irq(&tasklist_lock);
1229
1230         /*
1231          * This uses xchg to be atomic with the thread resuming and setting
1232          * it.  It must also be done with the write lock held to prevent a
1233          * race with the EXIT_ZOMBIE case.
1234          */
1235         exit_code = xchg(&p->exit_code, 0);
1236         if (unlikely(p->exit_state)) {
1237                 /*
1238                  * The task resumed and then died.  Let the next iteration
1239                  * catch it in EXIT_ZOMBIE.  Note that exit_code might
1240                  * already be zero here if it resumed and did _exit(0).
1241                  * The task itself is dead and won't touch exit_code again;
1242                  * other processors in this function are locked out.
1243                  */
1244                 p->exit_code = exit_code;
1245                 exit_code = 0;
1246         }
1247         if (unlikely(exit_code == 0)) {
1248                 /*
1249                  * Another thread in this function got to it first, or it
1250                  * resumed, or it resumed and then died.
1251                  */
1252                 write_unlock_irq(&tasklist_lock);
1253 bail_ref:
1254                 put_task_struct(p);
1255                 /*
1256                  * We are returning to the wait loop without having successfully
1257                  * removed the process and having released the lock. We cannot
1258                  * continue, since the "p" task pointer is potentially stale.
1259                  *
1260                  * Return -EAGAIN, and do_wait() will restart the loop from the
1261                  * beginning. Do _not_ re-acquire the lock.
1262                  */
1263                 return -EAGAIN;
1264         }
1265
1266         /* move to end of parent's list to avoid starvation */
1267         remove_parent(p);
1268         add_parent(p, p->parent);
1269
1270         write_unlock_irq(&tasklist_lock);
1271
1272         retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1273         if (!retval && stat_addr)
1274                 retval = put_user((exit_code << 8) | 0x7f, stat_addr);
1275         if (!retval && infop)
1276                 retval = put_user(SIGCHLD, &infop->si_signo);
1277         if (!retval && infop)
1278                 retval = put_user(0, &infop->si_errno);
1279         if (!retval && infop)
1280                 retval = put_user((short)((p->ptrace & PT_PTRACED)
1281                                           ? CLD_TRAPPED : CLD_STOPPED),
1282                                   &infop->si_code);
1283         if (!retval && infop)
1284                 retval = put_user(exit_code, &infop->si_status);
1285         if (!retval && infop)
1286                 retval = put_user(p->pid, &infop->si_pid);
1287         if (!retval && infop)
1288                 retval = put_user(p->uid, &infop->si_uid);
1289         if (!retval)
1290                 retval = p->pid;
1291         put_task_struct(p);
1292
1293         BUG_ON(!retval);
1294         return retval;
1295 }
1296
1297 /*
1298  * Handle do_wait work for one task in a live, non-stopped state.
1299  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1300  * the lock and this task is uninteresting.  If we return nonzero, we have
1301  * released the lock and the system call should return.
1302  */
1303 static int wait_task_continued(task_t *p, int noreap,
1304                                struct siginfo __user *infop,
1305                                int __user *stat_addr, struct rusage __user *ru)
1306 {
1307         int retval;
1308         pid_t pid;
1309         uid_t uid;
1310
1311         if (unlikely(!p->signal))
1312                 return 0;
1313
1314         if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1315                 return 0;
1316
1317         spin_lock_irq(&p->sighand->siglock);
1318         /* Re-check with the lock held.  */
1319         if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1320                 spin_unlock_irq(&p->sighand->siglock);
1321                 return 0;
1322         }
1323         if (!noreap)
1324                 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1325         spin_unlock_irq(&p->sighand->siglock);
1326
1327         pid = p->pid;
1328         uid = p->uid;
1329         get_task_struct(p);
1330         read_unlock(&tasklist_lock);
1331
1332         if (!infop) {
1333                 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1334                 put_task_struct(p);
1335                 if (!retval && stat_addr)
1336                         retval = put_user(0xffff, stat_addr);
1337                 if (!retval)
1338                         retval = p->pid;
1339         } else {
1340                 retval = wait_noreap_copyout(p, pid, uid,
1341                                              CLD_CONTINUED, SIGCONT,
1342                                              infop, ru);
1343                 BUG_ON(retval == 0);
1344         }
1345
1346         return retval;
1347 }
1348
1349
1350 static inline int my_ptrace_child(struct task_struct *p)
1351 {
1352         if (!(p->ptrace & PT_PTRACED))
1353                 return 0;
1354         if (!(p->ptrace & PT_ATTACHED))
1355                 return 1;
1356         /*
1357          * This child was PTRACE_ATTACH'd.  We should be seeing it only if
1358          * we are the attacher.  If we are the real parent, this is a race
1359          * inside ptrace_attach.  It is waiting for the tasklist_lock,
1360          * which we have to switch the parent links, but has already set
1361          * the flags in p->ptrace.
1362          */
1363         return (p->parent != p->real_parent);
1364 }
1365
1366 static long do_wait(pid_t pid, int options, struct siginfo __user *infop,
1367                     int __user *stat_addr, struct rusage __user *ru)
1368 {
1369         DECLARE_WAITQUEUE(wait, current);
1370         struct task_struct *tsk;
1371         int flag, retval;
1372
1373         add_wait_queue(&current->signal->wait_chldexit,&wait);
1374 repeat:
1375         /*
1376          * We will set this flag if we see any child that might later
1377          * match our criteria, even if we are not able to reap it yet.
1378          */
1379         flag = 0;
1380         current->state = TASK_INTERRUPTIBLE;
1381         read_lock(&tasklist_lock);
1382         tsk = current;
1383         do {
1384                 struct task_struct *p;
1385                 struct list_head *_p;
1386                 int ret;
1387
1388                 list_for_each(_p,&tsk->children) {
1389                         p = list_entry(_p,struct task_struct,sibling);
1390
1391                         ret = eligible_child(pid, options, p);
1392                         if (!ret)
1393                                 continue;
1394
1395                         switch (p->state) {
1396                         case TASK_TRACED:
1397                                 /*
1398                                  * When we hit the race with PTRACE_ATTACH,
1399                                  * we will not report this child.  But the
1400                                  * race means it has not yet been moved to
1401                                  * our ptrace_children list, so we need to
1402                                  * set the flag here to avoid a spurious ECHILD
1403                                  * when the race happens with the only child.
1404                                  */
1405                                 flag = 1;
1406                                 if (!my_ptrace_child(p))
1407                                         continue;
1408                                 /*FALLTHROUGH*/
1409                         case TASK_STOPPED:
1410                                 /*
1411                                  * It's stopped now, so it might later
1412                                  * continue, exit, or stop again.
1413                                  */
1414                                 flag = 1;
1415                                 if (!(options & WUNTRACED) &&
1416                                     !my_ptrace_child(p))
1417                                         continue;
1418                                 retval = wait_task_stopped(p, ret == 2,
1419                                                            (options & WNOWAIT),
1420                                                            infop,
1421                                                            stat_addr, ru);
1422                                 if (retval == -EAGAIN)
1423                                         goto repeat;
1424                                 if (retval != 0) /* He released the lock.  */
1425                                         goto end;
1426                                 break;
1427                         default:
1428                         // case EXIT_DEAD:
1429                                 if (p->exit_state == EXIT_DEAD)
1430                                         continue;
1431                         // case EXIT_ZOMBIE:
1432                                 if (p->exit_state == EXIT_ZOMBIE) {
1433                                         /*
1434                                          * Eligible but we cannot release
1435                                          * it yet:
1436                                          */
1437                                         if (ret == 2)
1438                                                 goto check_continued;
1439                                         if (!likely(options & WEXITED))
1440                                                 continue;
1441                                         retval = wait_task_zombie(
1442                                                 p, (options & WNOWAIT),
1443                                                 infop, stat_addr, ru);
1444                                         /* He released the lock.  */
1445                                         if (retval != 0)
1446                                                 goto end;
1447                                         break;
1448                                 }
1449 check_continued:
1450                                 /*
1451                                  * It's running now, so it might later
1452                                  * exit, stop, or stop and then continue.
1453                                  */
1454                                 flag = 1;
1455                                 if (!unlikely(options & WCONTINUED))
1456                                         continue;
1457                                 retval = wait_task_continued(
1458                                         p, (options & WNOWAIT),
1459                                         infop, stat_addr, ru);
1460                                 if (retval != 0) /* He released the lock.  */
1461                                         goto end;
1462                                 break;
1463                         }
1464                 }
1465                 if (!flag) {
1466                         list_for_each(_p, &tsk->ptrace_children) {
1467                                 p = list_entry(_p, struct task_struct,
1468                                                 ptrace_list);
1469                                 if (!eligible_child(pid, options, p))
1470                                         continue;
1471                                 flag = 1;
1472                                 break;
1473                         }
1474                 }
1475                 if (options & __WNOTHREAD)
1476                         break;
1477                 tsk = next_thread(tsk);
1478                 if (tsk->signal != current->signal)
1479                         BUG();
1480         } while (tsk != current);
1481
1482         read_unlock(&tasklist_lock);
1483         if (flag) {
1484                 retval = 0;
1485                 if (options & WNOHANG)
1486                         goto end;
1487                 retval = -ERESTARTSYS;
1488                 if (signal_pending(current))
1489                         goto end;
1490                 schedule();
1491                 goto repeat;
1492         }
1493         retval = -ECHILD;
1494 end:
1495         current->state = TASK_RUNNING;
1496         remove_wait_queue(&current->signal->wait_chldexit,&wait);
1497         if (infop) {
1498                 if (retval > 0)
1499                 retval = 0;
1500                 else {
1501                         /*
1502                          * For a WNOHANG return, clear out all the fields
1503                          * we would set so the user can easily tell the
1504                          * difference.
1505                          */
1506                         if (!retval)
1507                                 retval = put_user(0, &infop->si_signo);
1508                         if (!retval)
1509                                 retval = put_user(0, &infop->si_errno);
1510                         if (!retval)
1511                                 retval = put_user(0, &infop->si_code);
1512                         if (!retval)
1513                                 retval = put_user(0, &infop->si_pid);
1514                         if (!retval)
1515                                 retval = put_user(0, &infop->si_uid);
1516                         if (!retval)
1517                                 retval = put_user(0, &infop->si_status);
1518                 }
1519         }
1520         return retval;
1521 }
1522
1523 asmlinkage long sys_waitid(int which, pid_t pid,
1524                            struct siginfo __user *infop, int options,
1525                            struct rusage __user *ru)
1526 {
1527         long ret;
1528
1529         if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1530                 return -EINVAL;
1531         if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1532                 return -EINVAL;
1533
1534         switch (which) {
1535         case P_ALL:
1536                 pid = -1;
1537                 break;
1538         case P_PID:
1539                 if (pid <= 0)
1540                         return -EINVAL;
1541                 break;
1542         case P_PGID:
1543                 if (pid <= 0)
1544                         return -EINVAL;
1545                 pid = -pid;
1546                 break;
1547         default:
1548                 return -EINVAL;
1549         }
1550
1551         ret = do_wait(pid, options, infop, NULL, ru);
1552
1553         /* avoid REGPARM breakage on x86: */
1554         prevent_tail_call(ret);
1555         return ret;
1556 }
1557
1558 asmlinkage long sys_wait4(pid_t pid, int __user *stat_addr,
1559                           int options, struct rusage __user *ru)
1560 {
1561         long ret;
1562
1563         if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1564                         __WNOTHREAD|__WCLONE|__WALL))
1565                 return -EINVAL;
1566         ret = do_wait(pid, options | WEXITED, NULL, stat_addr, ru);
1567
1568         /* avoid REGPARM breakage on x86: */
1569         prevent_tail_call(ret);
1570         return ret;
1571 }
1572
1573 #ifdef __ARCH_WANT_SYS_WAITPID
1574
1575 /*
1576  * sys_waitpid() remains for compatibility. waitpid() should be
1577  * implemented by calling sys_wait4() from libc.a.
1578  */
1579 asmlinkage long sys_waitpid(pid_t pid, int __user *stat_addr, int options)
1580 {
1581         return sys_wait4(pid, stat_addr, options, NULL);
1582 }
1583
1584 #endif